It has been recently suggested that the following reactions: (a) phytylation of chlorophyllide a, (b) hydrolysis of chlorophyll a, and (c) transphytylation of methyl chlorophyllide a, once attributed to a single enzyme (chlorophyllase), are likely due to more than one enzyme. This present study will be an attempt to provide more substantiative evidence for the three enzymes proposed earlier using conventional protein methods on the enzymes, obtained from wheat seedlings and separated by gel chromatography and gel electrophoresis. In addition, studies will be made on the biosynthesis in vivo and in vitro of the proposed chlorophyll precursor, methyl chlorophyllide a. Studies on methyl chlorophyllide biosynthesis will include the use of suspected C14-methyl-labeled biological methyl donors to discern the probable methyl donor, as well as to assist in devising an assay method for the enzyme involved. Studies will then be done to determine whether or not a fourth enzyme or one of the three described above catalyzes the chlorophyllide a methylation reaction. Later studies will attempt to determine the plant physiological location of all (four?) of the enzymes by testing for the activity of each in various chloroplast fractions (e.g. stroma or grana, and if grana, photosystem I and/or II particles). It is anticipated that these studies will provide insight into the biochemical roles of these enzymes (e.g. biosynthesis, biodegradation, or involvement in photosynthetic processes). Finally, attempts will be made using various methods of study of metabolic control mechanisms (e.g. studies of the effects of substrate or products on the enzyme level in vivo or on the enzyme activities in vitro; studies on the effects of protein synthesis and transcription inhibitors with and without the presence of increased substrates on the levels of the enzymes in vivo) to discern possible roles for the proposed enzymes in the control of chlorophyll metabolism at the genetic or enzyme level.